I am going to try improving the 737-300's cockpit in my spare time. I have forked and changed the bulkhead and cockpit door textures. My spare time is somewhat limited, so I may not get anywhere very fast, but I will definitely make an effort.
If anyone would like to help, that would be great. One of the first things I am seeing that could be improved is the lack of switches, especially the ones between the pilot seats. They are all marked out in the textures, so all you have to do is make the model and edit the xml accordingly.
My fork is here: https://github.com/flyingfisch/737-300
In case anyone is interested, here is the new door texture: